The present invention relates to a system for measuring and analyzing electrochemical reactions associated with the field of chemistry, biology, physics, medicine, environmental engineering, energy science, electronics and their related fields.
In the chemical measurement technology utilizing a quartz crystal resonator as a sensing element, there has been known a conventional method of measuring a resonant frequency variation indicative of a surface mass deposition on an electrode of the resonator or indicative of a viscosity and density variation of a fluid in contact with the resonator electrode. This method is applied such that, for example, the resonant frequency variation of the quartz crystal resonator is monitored during the course of an electrochemical reaction so as to analyze the electrochemical reaction, such as, formation of an electrolytically polymerized film or the corrosion of an electrode. On the other hand, the inventors have proposed another method based on the fact that a resonant resistance variation is caused by a viscosity and density variation in a surrounding fluid or in a viscoelastic coating film disposed in contact with an electrode surface on the resonator.
In the conventional electrochemical measurement method, the frequency variation is monitored to analyze a film deposition on the electrode surface or an electrode corrosion during the course of a tested electrochemical reaction. The monitored variation is treated straightforwardly to reflect mass variation. The resonant frequency variation may generally accurately reflect the mass effect on the surface of the quartz crystal resonator; however, in the case where a viscoelastic film is formed on the resonator by a certain electrochemical reaction, it is practically difficult to accurately monitor a deposit mass of the viscoelastic film due to attenuation of the resonator vibration through the film. Therefore, it is important in the electrochemical measurement method utilizing the quartz crystal resonator to evaluate the nature of the film in order to analyze the film deposition reaction. From a different point of view, the conventional measurement method can only monitor a film deposition or growth process which occurs directly on the electrode surface during the course of the electrochemical reaction. Further, as mentioned before, only the resonant frequency variation is measured and the measurement results are treated straightforwardly to detect a mass deposit variation. In the case where a functional or sensitive film is provisionally applied over the electrode surface, the charge and discharge of active substances into and from the sensitive film is analyzed in terms of mass variation by the measurement of the resonant frequency variation alone according to the prior art, and hence it is difficult to discriminate actually between the viscous variation and the mass variation within the sensitive film. Accordingly, it would be certainly necessary to measure the resonant resistance variation which reflects both the viscosity variation and the mass variation which occur by the electrochemical reaction within the sensitive film over the quartz crystal resonator, as well as to measure the resonant frequency variation.